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Effect of secondary impacts on SPT rod energy and sampler penetration / Changho Lee in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 522-526 Titre : Effect of secondary impacts on SPT rod energy and sampler penetration Type de document : texte imprimé Auteurs : Changho Lee, Auteur ; Jong-Sub Lee, Auteur ; Shinwhan An, Auteur Article en page(s) : pp. 522-526 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Secondary  impact  Standard  penetration  test  (SPT)  Energy  transfer  ratio Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper explores the standard penetration test (SPT) hammer-anvil behavior and investigates the effect of secondary impact on SPT energy and sampler penetration. It is observed that the hammer-anvil behavior after the impact depends on the characteristics of the wave reflected from the sampler. The type-I secondary impact, which is dominant for N<25, is induced due to the rapid downward movement of the anvil and the recontact of the following hammer on the rebounding anvil. The maximum energy calculated by integrating force and velocity (EFV) is achieved immediately after the occurrence of the type-I secondary impact and an additional sampler penetration is triggered by the type-I secondary impact. The type-II secondary impact, which is dominant for N>50, is produced by the restrike of the pushed-up hammer on the resting anvil. The type-II secondary impact causes only recoverable anvil deformation and does not contribute to the maximum EFV energy. For N-values of 25–50, both or either types of secondary impacts happen. As N-value increases, the type-I secondary impact fade away progressively and the type-II secondary impact becomes more distinctive. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Effect of secondary impacts on SPT rod energy and sampler penetration [texte imprimé] / Changho Lee, Auteur ; Jong-Sub Lee, Auteur ; Shinwhan An, Auteur . - pp. 522-526. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 522-526 Mots-clés : Secondary  impact  Standard  penetration  test  (SPT)  Energy  transfer  ratio Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper explores the standard penetration test (SPT) hammer-anvil behavior and investigates the effect of secondary impact on SPT energy and sampler penetration. It is observed that the hammer-anvil behavior after the impact depends on the characteristics of the wave reflected from the sampler. The type-I secondary impact, which is dominant for N<25, is induced due to the rapid downward movement of the anvil and the recontact of the following hammer on the rebounding anvil. The maximum energy calculated by integrating force and velocity (EFV) is achieved immediately after the occurrence of the type-I secondary impact and an additional sampler penetration is triggered by the type-I secondary impact. The type-II secondary impact, which is dominant for N>50, is produced by the restrike of the pushed-up hammer on the resting anvil. The type-II secondary impact causes only recoverable anvil deformation and does not contribute to the maximum EFV energy. For N-values of 25–50, both or either types of secondary impacts happen. As N-value increases, the type-I secondary impact fade away progressively and the type-II secondary impact becomes more distinctive. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]